[Al Skierkiewicz]

OK,
When trying to impart the wisdom of others, one thing to point to is the signature of guys like Don and I. I am a broadcast engineer and Extra Class Ham Radio operator. Don is a Ham with significant digital experience. Alan is a trusted network and software specialist with a lot of wireless experience.
Aluminum at 5 GHz might as well be lead.
For everyone, the DAP-1522 has two antennas mounted on the board. They are verticaly polarized with respect to the bottom of the AP/Router. That means they are most sensitive to radiation out to the sides, front and back of the radio. The circuit board is a ground plane effectively blocking all reception in that direction (out the bottom of the radio). The nature of 802.11N is that both antennas are required for max bandwidth to be achieved. Both are used for receive and transmit. In addition to the shielding effect provided by metallic objects, the metal serves to de-tune the antennas making them less effective. This effect, of course, is distance dependent. As Alan has pointed out, there is some significant noise generators on the robot. Of those that are the worst for interference is open frame motors (those that you can actually see sparks through the openings in the sides of the motors), the five volt convertor power supply, and the supplies in both the PD and the DSC. These noise sources not only interfere with radio reception, they also impart noise directly to the electronics on the board.
Having the radio mounted in the robot such that is "visible" to the antennas on the field, it is not mounted near a noise source and it is not surrounded by metal of any kind is the best of all worlds.
One word on "visibility", inspectors want to be able to help you and insure that you will play all matches at every event. If your mounting is questionable it may pass, but if you want help when you fail on the field, you have to meet us halfway. If we can't see the lights from several feet away when you are dead in the middle of the field, we have to rely on the field logs only, to try and figure out what went wrong. After repeated connection issues or a string of bad packet events we will ask you to move the radio to help you improve.